1. Technical Field
The present disclosure relates to a display device with a touch detection function.
2. Description of the Related Art
In recent years, attention has been paid for a touch detection device that can detect an external proximity object, or so-called a touch panel. The touch panel is used for a display device with a touch detection function that is mounted on or integrated with a display device such as a liquid crystal display device. The display device with a touch detection function causes the display device to display various button images and the like so that information can be input through the touch panel in place of normal mechanical buttons.
Japanese Patent Application Laid-open Publication No. 2013-065301 (JP-A-2013-065301) discloses a display module with a touch sensor integrated therein. The display module disclosed in JP-A-2013-065301 detects a noise level by analyzing detection signals from the touch sensor, and changes the mode of drive signals for the touch sensor, thus being capable of reducing the noise. Japanese Patent Application Laid-open Publication No. 2005-164709 (JP-A-2005-164709) discloses a display system constituted by an input device including conductive thin plates and a display device. The display system disclosed in JP-A-2005-164709 applies a noise cancelling signal having the same amplitude and phase as those of a drive signal applied to the display device to the input device so as to reduce temporal variation in electric field acting on an electric charge present between the display device and the input device, thus reducing noise, vibration, and unpleasant sound.
In the display module disclosed in JP-A-2013-065301, in order to detect the position of a touch input, limitation is imposed on, for example, the drive frequency of the drive signals supplied to the touch sensor. This may lead to a case where the drive signals are difficult to be changed so as to reduce the noise. The display system disclosed in JP-A-2005-164709 includes a noise cancelling signal generator for generating a noise cancelling signal in addition to a circuit for generating the drive signal. This may increase power consumption. In addition, although the noise decreases in members (such as the conductive thin plates) that have received the noise cancelling signal, noise may occur in a power supply circuit for generating the drive signal, for example.
For the foregoing reasons, there is a need for a display device with a touch detection function capable of suppressing noise.